1. Field of the Invention
The present invention relates to a synchronization control method and synchronization control device for synchronous driving of two or more movable axes, of an industrial device, construction device, or the like, in which synchronization control is performed.
2. Description of the Prior Art
In a conventional synchronization control method, one movable axis is taken as a master axis, and another movable axis is driven and controlled as a slave axis in synchronism with the master axis. In this case, the displacement of the slave axis is determined in accordance with the phase of the master axis, starting from a master axis phase of 0° until a complete revolution. Therefore, the slave axis is simply able to repeat the same operation, and it is not possible to change the operation of the slave axis during operation, in accordance with the state of the machine, or to repeat a specific operation.
FIG. 1 is an example showing the displacement y of the slave axis corresponding to respective phase θ in one revolution of the master axis which rotates one revolution through 360°. Furthermore, FIG. 2 is an illustrative diagram of a data table recording the displacement y of the slave axis corresponding to a phase θ of the master axis. As shown in FIG. 1 and FIG. 2, the displacement y of the slave axis is determined in accordance with the phase θ of the master axis, which is changing moment by moment. The master axis is usually constituted by a rotating shaft, and since the angle of rotation thereof returns to 0° when it exceeds 360°, it is capable of repeating exactly the same operation.
Moreover, if the operation of the slave axis is different for respective revolutions of the master axis, then it is necessary to input all the data for a plurality of revolutions, and hence the amount of data will increase in size. Moreover, although a sub-program method which calls up separate displacement data is commonly known, this method requires call-up processing, and therefore it has a drawback in that the pulses are interrupted at the junctions between different displacement data, and hence machining work or processing is not performed smoothly at junctions between displacement data.
Moreover, Japanese Patent No. 3220588 proposes a method wherein a plurality of cam-shape data tables are previously registered, and by combining these tables, the cam shape is modified, but the cam shape can only be modified by combinations of the registered patterns, and in order to form a desired cam shape, it is necessary to register this shape anew.
As described above, in a conventional synchronization control method, since the displacement of the slave axis is synchronized with one revolution of the master axis, from the 0° angle of the master axis, it is not possible to change the operation of the slave axis during operation of the master axis, in other words, in accordance with the state of the machinery, or to repeat particular operations. Furthermore, a problem occurs in that repeated sections must also be specified, and therefore the volume of data becomes very large.
There is also a method wherein repeated data is called up by a sub-program, or a method wherein the data is divided into a plurality of sets, but the data becomes fixed and cannot be adapted or used if the operational state is changed.